Figure 1. A stable nuclear basket is bound to a double nuclear ring.

(A) Cross-sectional views along the central axis (dashed line) of the in-cell cryo-ET maps of yNPC with single and double NR variants, mNPC and pNPC. The nuclear basket is resolved for the mNPC and yNPC with a double NR. The location of cytoplasmic filaments for the mNPC CR are indicated by teal open triangles in (A) and (B).

(B) Cytoplasmic views of the CR of yNPC with a single CR, mNPC with a double CR, and pNPC with an incomplete CR. Also depicted are models of the single or double Y-complex and the adjoining mRNA export platform (highlighted in the gray schematic), whose eight copies are arranged in head-to-tail orientation around the central axis to form the CR. Shown in dashed teal lines is the region from which the cytoplasmic filaments emanate.

(C) Nucleoplasmic view of the single and double NR of yNPC and double NR of mNPC and pNPC along with the models of the single or double Y-complex. Shown in dashed green lines is the region in double NR from which the basket’s struts emanate. The models for yeast and mammalian CR/NR are from the PDB IDs: yNPC, PDB: 7N9F; mNPC, PDB: 7R5J.

(D) Nucleoplasmic views of the yeast and mammalian basket. CR, cytoplasmic ring; IR, inner ring; NR, nuclear ring; NE, nuclear envelope; LR, lumenal ring. See also Figures S1 and S2.